Apparatus for assembling potentiometers



Oct. 3l, 1950 J. o. HAMILTON ETAL APPARATUS FOR AssEMBLINGPOTENTIOMETERS 3 sheets-sheet 1 Filed July 20, 1945 /Nl/EA/rops J. O. HAM/L TON L. J. ROZ NKOWSK/ OOOOO O O G O O Oct. 31, 1950 J. o. HAMILTONvETAL 2,527,812

APPARATUS FOR AssEMBLING POTENTIOMETERS Filed July 20, 1945 :ssheets-sheet ,1

IM In (LLLA v /NVENTORS J. O. HAM/L TON By L. JJROZA KOWSK/ A TTORNEYOct. 3l, 1950 J. o. HAMILTON ETAL APPARATUS FoR AssEMBLING PoTENToMETERs3- Sheets-Sheeb 3 Filed July 20, 1945 n ut.

N v n M OLK ,o T/N T M M A. T VAZ 4A WH0 R JJ A LV B l/Q Y Patented Oct.31, 1950 APPARATUS FOR ASSEMBLING POTENTIOMETERS James 0. Hamilton,Dundalk, and Leon .1L Rozankowski, Baltimore, YMd., assgnors to WesternElectric Company, Incorporated, New York, N. Y., a corporation of NewYork Application .uly.20, 1945, Serial No. 606,217

1 claim. 1

This invention relates to apparatus for `assembling articles, and hasfor its object the provision of new and improved apparatus forassembling articles.

One fixture embodying the invention serves to assemble :and test apotentiometer which includes a potentiometer card, a pointer, a dialhaving a scale thereon and movable with respect to the potentiometercard and the pointer, and a brush assembly designed to be secured to thedial for movement therewith for contacting the potentiometer card.Thexture includes means for fastening the potentiometer card and thepointer in fixed positions, a test set associated with said means fordetermining the location of the brush assembly with respect to thepotentiometer card, and means Vfor holding the dial stationary withrespect to the potentiometer card and the pointer so that the brushassembly may be located correctly with respect tothe dial and thepotentiometer card and fastened tothe with a, potentiometer card and apointer rigidlyV mounted on the baserplate held in fixed posi` tions,means for clamping `a dial having a `scale formed thereon of thepotentiometer in a predetermined position with respect to the pointer,means for adjusting the position of the clamping means to adjust theposition of the dial with respect to the pointer, a screwdriver,A apivotally mounted arm carrying ,a screwdriver for positioning it inoperative engagement with a rotatable shaft of the potentiometer, a testset for locating the position with respect to the potentiometer card ofa brush assembly carried by the shaft of the potentiometer, means forclamping the screwdriver against rotation relative to the dial after thebrush assembly has been moved to a position on the potentiometer cardcorresponding to the reading of the pointer on the scale so that theshaft may be secured to the dial in that position, and means forapplying a predetermined 'torque to the screwdriver to test thefastening of the shaft to the dial.

A complete understanding of the invention may be obtained from thefollowing detailed description of an assemblying xture forming oneembodiment thereof, when read in conjunction with the appended drawings,in which:

Fig. 1 is a top plan View of an assemblying fixture embodying theinvention, with portions thereof broken away;

Fig. 2 is a fragmentary front elevation of the fixture shown in vpartialsection;

Fig. 3 is a fragmentary vertical section taken along line 3-3 of Fig. l;

Fig. 4 is a fragmentary -sectional View taken along line 1iof Fig.- 3';and Fig.15 is a diagrammatic. View of an electrical circuit embodied inthe fixture. a

Referring now in detail to the drawings, there is shown therein afixture l@ (Fig. l) for assemblying and testing a potentiometer i i,which includes stationary pointer i2 formed on a base 22,

land has a scale .i3 formed on a rotatable dial Iii thereof. A brushassembly I5 contacts a resistance wire I6 of an annular potentiometercard 20 and may be moved along the resistance wire. The annularpotentiometer card is fas.- tened to a cylindrical projection 2i formedvon thebase 22, and a shaft 23 is rotatable on axis forming the center ofthe annular potentiometer card. The brush .assembly i5 is rigidlyfastened to the shaft 23, and a collar 2li' (Fig. 3)

having an externally threaded chuck portion 25 is positioned over theshaft. A nut 2t threaded onithe chuck portion may be tightened, afterthe brush assembly I5 `and the dial I4 have been orientated with respectto each other, to secure the collar 2t rigidly to the shaft so that norelative movement can occur between brush assemblt7 `I5 and the dialifi. This also secures a disc 30 fastened rigidly to the collar 2i tothe shaft 23.

The zero end of the resistancewire I6 is connected by a lead I'! to aterminal post i8, and the unity end thereof is connected by a lead I9 toa terminal post 28. A brush assembly 27 connects the brushassembly I5toa slip ring 29, which is connected by a conductor 3i to a terminalpost 38. The terminal posts project into an annular cavity 3S for-med inthe base 22 of the potentiometer Ii at predetermined points therein. Aring il (Fig. 4) made of insulating material and having sockets 48-48formed therein for receiving the terminal posts I3, 22 and t ts into theannular cavity 33 (Fig. 3). A plurality of resilient contactors dil-1X9secured to the ring project into the sockets and Contact the terminalposts.

The ring II'I is Vfitted into the annular cavity 39 in the base 22 ofthe potentiometer and the contactors L12-4Q contact the terminal postsI3, 28 and 38, which project into the sockets iB-48 formed in the ring.With the nut 26 loosened, the potentiometer II is placed upon a baseplate 29 supported by posts 3 I-3I (Fig. 2) and thumbscrews532-"3Z- arethreadedl into tappedbores 33-33 formed in the base 22 of thepotentiometer to orientate the base, the annular potentiometer card 2Band the pointer I2 with respect to the fixture I0. A conductor 34connected to a resistance 53 of an adjustable test set 35 for measuringratios of resista-hoes of portions of the resistance wire IB to theresistance of whole resistance wire connects to the contactor connectedto the terminal post I8 to one end of the resistance e3. A secondconductor 35 oi the test set 35 connects to the contacter, whichcontacts the terminal post 25, to the other end or" the resistance d3,and a third. conductor S3 connects the terminal post 33 to agalvanometer lVwhieh is connected adjustably by a conductor 52 to theresistance L33 of the test set 35. The ends of the resistance i3 areconnected to a source d?, of electrical potential by conductors 135 and5. The test set 35 serves to indicate whether the position of the brushassembly I with respect to the resistance wire I5 corresponds to theposition of the conductor Q2 on the resistance 43 in a manner well knownto those skilled in the art or electrical testing.

The dial I4 then is moved, if necessary, to a position in which thepointer I2 reads zero on the scale I3 formed on the dial III. Amicroscope 98 mounted on an arm 99 rotatably mounted on the base plate29 enables an operator of the xture I8 to take the reading of thepointer I2 on the scale I3 with a high degree of accuracy. The disc 3B(Fig.'2) extends over a lower jaw 50 formed on a tongue 5I. A plate 52of L-shaped cross section is bolted to the lower jaw 5@ and an upper jaw53 is mounted on the plate 52 by a pair of thumb screws 5ii-5ll, whichpass through tapped bores 55--55 formed in the plate 52. The thumbscrews55-53 may be threaded farther through the bores 55-55 to force the upperjaw 53 against the plate 3B to clamp the plate-35 tightly between thejaws 50 and 53.

The tongue 5I is secured between a plate 51 and a block 59, which areseparated by spacers 58-55, by a pin 5S, which projects through anarcuate guide slot 5i? formed in the plate 5'! concentrically withrespect to the shaft 23, a bore 6I formed in the tongue 5I and anarcuate guide slot 62 formed in the block 59. The guide slot 62 isparallel with the guide slot 66, and the pin 56, which may be removedfrom the arcuate guide screwdriver 'I I.

vchecked by the test set 35.

After the dial I4 has been clamped in a position in which the pointer I2reads zero on the scale I3, as described hereinabove, the plate 66 isrotated in a clockwise direction, as viewed in Fig. 3, to the positionin which it is shown in Fig. 3, and the bit 'I2 of the screwdriver 'IIis positioned in a slot 'I'I formed in the shaft 23 and holds the shaftagainst rotation relative to the A switch I5 (Fig. 5) positioned in theconductor d6 then is closed and the screwdriver 'II is rotated to rotatethe brush assembly I5 to a position in which it contacts the zero end ofthe resistance wire I5, which position is y A bolt (Fig. 2) having a`shoulder 8i formed thereon projects through an untapped bore 82 formedin the slots and the bore 6I holds the tongue 5I against longitudinalmovement when it is positioned in the guide slots and the bore 6I, Apair of diametrically opposed thumbscrews (i3-63 (Fig. l) hold thetongue 5| against lateral movement.

After the disc 35 has been clamped between the upper jaw 53 and thelower jaw 55, the thumbscrews [i3-63 may be manipulated to rotate thetongue 5| about the axis of the shaft 23 so that the plate 3i? and thedial I4 also may be rotated. This permits adjustment of the dial Id withrespect to the pointer I2 within close limits after the disc 3D has beenclamped. After the dial is so adjusted, the thumbscrews 53-53 and thepin 6I hold the plate 3i! and, therefore, the dial I4 in their adjustedpositions.

A split plate 66 (Fig. 3) pivotally mounted on a bracket 6l secured tothe .base plate 29 serves to mount a screwdriver 'Il in a bore 'I3formed in its free end. The screwdriver is provided With a knurled knob1G, a cylindrical shank portion 88, a removable collar 89 and a bit l2.Slots 'I8 and 'I9 formed in the split 'plate l(iI form clamping arms 'I5and 'I6 (Fig. 2), whereby a clamping collar is formed on the end of theplate 66.

clamping arm it and is threaded into a tapped bore 83 formed in theclamping arm l5. A handle 24 is used to screw the bolt 85 into thetapped bore 83 to clamp the screwdriver 'II against rotation relative tothe plate 66, or unscrew the bolt to loosen the screwdriver.

After the brush assembly I5 has been moved to the Zero end oi theresistance wire I6, the bolt 8G is threaded farther into the tapped bore83 formed in the arm l5, whereby the screwdriver 'II is clamped againstrotation relative to the plate 66 so that the shaft 23 and the brushassembly I5 are'held against movement relative to the resistance wire EGand the dial Ill. The nut 25 then is screwed farther upon the externallythreaded chuck portion 25 and causes the chuck portion to rmly grip theshaft 23. rlhus, the brush assembly I5 is secured to the dial I4 in apredetermined position with respect thereto. The bolt 83 then isloosened so that the screwdriver 'II is free to rotate with respect tothe plate B6.

A tang 953 (Fig. l) of a torque wrench SI of a suitablek construction istted into a socket 92 formed in the screwdriver, and a predeterminedforce is applied to the torque wrench 5I, which force is transmitted tothe shaft 23 by the screwdriver lil. If the chuck portion 25 of thecollar 2A is fastened securely to the shaft 23, rotation of the shaft 23is prevented as the disc 30 is secured by the upper jaw 53 and the lowerjaw 55 and the collar 2li securely fastens the disc to the cover lli.But ii the chuck portion 25 is not fastened securely to the shaft 23,this force will cause the shaft 23 to be rotated relative thereto, whichfact may oe noted andthe nut 25 can be threaded more tightly upon thechuck portion 25 after reorientating the brush assembly I 5 with respectto the cover U5.

After the brush assembly I5 has been secured in an orientated positionwith respect to the dialV l5, the tang 5t of the torque wrench SI iswithdrawn from the socket 92 of the screwdriver 'II, and the thumbscrews55--54 (Figs. l and 2) are actuated tcmove the upper jaw 53 away fromthe disc 35 to unclamp the disc 3i). The screwdriver II then may be usedto turn the shaft 23, the brush assembly I5 and the dial I4 as a unitwith respect to the potentiometer card 20 and the pointer I2, and ratiosof resistance of portions o the resistance wire I6 with respect to theresistance of whole wire may then be checked by the test set 35 forpredetermined readings of the pointer I2 on the scale I3. After thepotentiometer II has been so tested, the split plate 66 is pivoted in acounterclockwise direction, as viewed in Fig. ,3, the thumbscrews 5ft-54are loosened, the thumbscrews 32-32 are Withdrawn from the tapped bores33-33, and the assembled and tested potentiometer I I may be removedfrom the fixture I0.

In the operation of the xture IIJ, the plate 85 (Fig. 3) is rotated incounterclockwise direction to a position of rest spaced over 90 from theposition in which it is shown in Fig. 3. The ring 41 is tted over theterminal posts I8, 28 and 38 and into the annular cavity 39 so that theends of the resistance wire I5 and the brush assembly I5 are connectedelectrically with the test set 35. The potentiometer II then is placedon the base plate 29, and the thumbscrews 32-32 are screwed into thetapped bores 33-33 formed in the base 22 of the potentiometer to securethe base 22, the potentiometer card and the pointer I2 in stationarypositions with respect to the fixture.l

The dial I4 then is moved to position in which the pointer I2 readsapproximately zero onA the scale I3 (Fig. 2), and. the thumbscrews 54-54are actuated to clamp the plate 38 between the lower jaw 59 and theupper jaw 53. The thumbscrews 63-63 (Fig. l) then are adjusted to movethe dial I4 though the tongue 5I, the jaws 50 and 53, the disc 30 andthe collar 24 to a position in which the pointer reads exactly zero onthe scale I3, which reading is determined within close limits by themicroscope 98 (Fig. 3), which is swung to a convenient position by thearm 99.

After the dial I4 has been secured in a position in which the pointer I2(Fig. 2) reads zero on the scale I3, the split plate 36 is swung in aclockwise direction, as viewed in Fig. 3, and the bit 'I2 of thescrewdriver 'II is inserted into the slot I1 formed in the shaft 23. Thescrewdriver II then is turned to move the brush assembly I5 to the zeropoint of the resistance wire I6, which position is determined by thetest set 35, and the bolt 80 is turned to clamp the screwdriver 1I inthat position. The nut then is threaded tightly upon the chuck portion25 to fasten the chuck portion 25 securely to the shaft23, and the bolt80 is actuated to loosen the screwdriver 'II with respect to the plate66.

The torque wrench 9! (Fig. 1) then is used to test the degree oftightness with which the chuck portion 25 of the collar 24 gripstheshaft 23. If the chuck portion 25 does not grip the shaft 23 tightlyenough, the brush assembly I5 is reorientated with respect to the dialI4 in the manner indicated hereinabove and the torque wrench again isutilized to test whether the chuck portion 25 grips the shaft 23 tightlyenough. If the chuck portion does grip the shaft 23 tightly enough, thedisc is unclamped and the screwdriver 'II is actuated to rotate the dialI4 to a y Number 6 of the entire resistance wire is correct for thereading of the pointer I2 on the scale I3. This operation is repeateduntil all the ratios which it is desired to check have been checked.

The plate 55 then is turned in a counterclockwise direction, as viewedin Fig. 3, the thumbscrews 32-32 are withdrawn from the tapped bores33-33 formed in the base 22, and the ring 4l and the contactors 49-49are drawn from engagement with the terminal posts I3, 28 and 38. Thexture I0 then may be utilized to test another potentiometer like thepotentiometer II.

The fixture Il) accurately locates the brush assembly I5 with respecttothe potentiometer card 20 and the scale I3 on the dial I4 and holdsthe brush assembly I5 in its located position while the nut 26 isthreaded upon the externally threaded chuck portion 25 of the collar 24to secure the shaft 23 and the brush assembly I5 rigidly to the dial I4.It also provides a test of the tightness of the connection between thechuck portion 25 and the shaft 23 and tests the various ratios ofresistances of the assembled potentiometer II for the desired readingsof the .pointer I2 on the scale I3.

What is claimed is:

An apparatus for adjusting an article composed of at least three parts,which comprises a base member for securing one of the parts, a sideclamp member on the base member for holding another of the parts againstrotation relative to the first part, a plate having a slot extendinglongitudinally thereof to form a pair of arms, said plate having a boreformed therein in communication 4with the slot, a screwdriver rotatablymounted in the bore, and means for drawing arms together to clamp thescrewdriver therebetween, the screwdriver serving to engage a thirdpart, whereby rotation of the screwdriver will cause relative movementbetween said third part and said clamping member holding said secondpart toV thereby finally position said parts.

vJAMES O. HAMILTON. LEON J. ROZANKOWSKI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date 950,548 Frost Mar. 1, 1910 1,694,164Crosthwait Dec. 4, 1928 1,800,209 Christopherson Apr. 14,1931 1,829,557Ewing Oct. 27, 1931 1,870,462 McWeeny Aug. 9, 1932 2,169,063 Wensley etal Aug. 8, 1939 2,459,228 Konicek et al Jan. 18, 1949 FOREIGN PATENTSNumber Country Date 391,124 Great Britain Apr. 18, 1933-

